Usually you would sell your game on indie sites like http://www.gog.com/ , https://indiegamestand.com/ , http://www.desura.com/ or post on greenlight to get on steam.com . I don't think BB has the option to include ads for .exe export
That's if you can even get Buildbox to export to a Windows EXE file. Does not work correctly from what I have seen and heard. I spoke with support and they said they are aware of a glitch and working on it.
Well this is what it does to me. The entire left have of my game is missing, and if I change the window size, the black area on the right slowly scans to the left and then jumps back to the right and keeps doing that.